Refining of oils, fats, and waxes



Patented Jan. 13, 1942 UNITED STATES REFINING F OILS, FATS, AND WAXES Hugo J. Kauifmann, Buffalo, N. Y., assignor to Buflalo Electra-Chemical Company, Inc., Buftalc, N. Y.

No Drawing. Application January 27, 1940, Serial No. 316,047

g 2 cum The preeent invention relates to the refinin of oils, fats and waxes by the employment of chlorine dioxide, and more particularly to the refining of such materials by solution of chlorine dioxide in the material to be bleached.

In accordance with the present invention, colored organic materials are refined and bleached by treating the same with an explosive oxide of chlorine. under conditions where the explosive hazard is substantially eliminated and wherein bleaching occurs.

A novel feature of my invention is to direct the explosive gaseous oxide of chlorine substantially immediately upon formation into the oil. To this end, the oxide is produced in a reaction zone adjacent the material to be bleached and passes directly from the zone through an interface or surface of contact between the chemicals generating the gas and the material being treated and into the latter.

I have discovered that chlorine dioxide is compatible with and soluble in oils, fats and waxes generally, and particularLv in those materials liquid at room temperature or readily liquefiable so that the temperature of treatment is not so great as to decrease the solubility of the gaseous bleaching agent. Thus, I have successfully bleached prime yellow cotton seed oil (oil neutralized with caustic soda) by permitting chlorine dioxide to seepslowly into and through the oil, the chlorine dioxide being readily dissolved therein and producing, after a short period of time, substantial color reduction in the oil. In this treatment the color of the oil is first momentarily darkened and then becomes lighter until a bleached product results.

In the same fashion it is possible to produce substantial color reduction in fatty substances of the types exemplified by palm oil, linseed oil, soya bean oil, as well as certain liquid and semisolid fats. Additionally, ester type waxes, such as beeswax, may be bleached by my method.

Due to the extremely explosive nature of chlor'ine dioxide, I have found it-advisable in some instances to dilute the chlorine dioxide with an inert gas, as, for instance, oxygen or carbon dioxide. Where the chlorine dioxide is produced in situ, dilution of the gas is not a necessity but may be resorted to as a precautionary measure. Thus, oxalic acid may be added to the reaction mixture from which the chlorine dioxide is obtained and decomposed with the production of carbon dioxide which mingles with and dilutes the chlorine dioxide with elimination of the explosive hazard.

The chemicals are added to the reaction zone in such a manner that no chlorine dioxide is developed before the reaction mixture is brought in contact with the material to be treated. In some after a period of a few minutes to several hours contact in the presence of from about .05 to about i 5.0% of active chemical, based upon the weight of the material to be treated. It will be understood, of course, that the quantity of active chem-' ical employed in bleaching will be determined by the nature of the material treated and the desired degree of bleaching to be obtained.

As an example of the production of chlorine dioxide, a mixture of a chlorate. such as potassium or sodium chlorate, and oxalic acid is treated with sulfuric acid of about 10 to 50% strength. Chlorine dioxide, mixed with carbon dioxide, is evolved and difiuses into the organic material to be bleached. Danger of explosion is eliminated due to the solubility of the gas in oils, fats and waxes, and furthermore the explosive hazard is still further reduced by the presence of the inert gas.

The following are examples of the, procedure illustrative of the invention:

Example 1 1 g. of sodium chlorate, 1 g. of oxalic acid, 2.5 cc. of 45% sulfuric acid, and 100 g. of yellow refined cotton seed oil are placed into a container, the bottom of which can be heated by steam. Heat up slowly, and gradually raise the temperature to 90 C. within approximately one hour. Already at lower temperature chlorine dioxide and carbon dioxide evolve and the gases penetrate into the supernatent layer of oil. The carbon dioxide forms a foam on the surface of the oil and escapes into the surrounding air.

The color of the oil deepens in the beginning from yellow to brown and then turns lighter and lighter. The aqueous acid solution at the bot- 55 tom is drawn off and the oil is subsequently instances, the oil, fat or wax is added to thewashed with water, with diluted sodium carbonate solution and again with water.

Example 2 Example 3 100 g. of beeswax are added to 2 g. sodium chlorate and 12 cc. of 20% sulfuric acid. This mixture is heated up to 70 C. until the wax is melted. Then 2 g. of oxalic acid are added and the mixture is heated while stirring only occasionally and slowly for about 1 hours until the temperature has reached 90 C. The solution at the bottom is drawn of! and the wax is then treated with hot water in order to remove residues of acid and salts. V I

Example 4 100 g. of soya bean oil are mixed with 5 cc. of technical sodium chlorite and stirred slowly while adding 5 cc. of 10% sulfuric acid. The oil becomes brown at first and within a few minutes turns lighter and lighter. time was about hour.

Bleaching Example 5 g. refined cotton seed oil are'mixed with 10 cc. of 10% solution of sodium chlorite and 10 cc. of a buflered acetic acid solution which contains 18 g. acetic acid and 57.4 g. sodium acetate per liter. The mixture is stirred slowly while adding 3 cc. of 3.7% solution oi! formaldehyde. The mixture rapidly turned a deeper shade, but within half an hour the color became lighter.

Subsequent to the action of chlorine dioxide, the treated oil, fat or wax is given a wash with a mild alkali and then with water to neutrality.

I claim:

1. The method of refining oils, fats and waxes which comprises generating chlorine dioxide in the presence of but in a zone in contact with and below the material'to'be bleached whereby the same diffuses into. the oil, fat or wax to be bleached,and permitting the mixture to stand to effect the desired bleaching action.

2. The method of refining oils, fats'and waxes bleached whereby the mixed gases difi'use into the material to be bleached. Q 

